1. Field of the Invention
The present invention relates to an assembly for electronically processing images. More particularly, the present invention relates to an image processing assembly used with an electrophotographic copying machine, which can produce an image of data from a copying device combined with electronic data prepared by personal computers, word processors or the like.
2. Discussion of the Related Art
An electrophotographic copying machine having high copying speed and high copy quality is frequently used in combination with an automatic document feeder, a sorter receiving different sets of copies, and the like. Such a systematized copying machine saves a great deal of labor.
In the conventional electrophotographic copying machine, light reflected on the surface of an original document is guided and imaged on a photoreceptor by means of a lens. Accordingly, the input of an image and the exposure of the photoreceptor to the light progresses concurrently. This indicates that the conventional copying machine only functions to copy original documents. Recently, a digital copying machine has been developed and used, which receives image data from an input image terminal, electronically processes the image data, and outputs through an image output terminal.
FIG. 7 is a block diagram showing a digital copying machine capable of electronically processing image data.
In the digital copying machine, an image input terminal (IIT) 20 reads an image on an original document by using a CCD line sensor, and converts an analog video signal as gathered into a digital signal. An image processing system (IPS) 21 executes signal correction and the like, converts the corrected signal into a two-level signal, and stores it into a data storage unit 22.
In an image output terminal (IOT) 23, the two-level data is read out of the storage unit, while a light source, such as a laser, is turned on and off according to the two-level data, forming pixels on the photoreceptor. In this way, the image of the original document is reproduced.
With the digital copying machine handling digital image data, an attempt has been made to couple the copying machine with external devices, such as personal computers (PCs) and facsimile (FAX) machines. The IOT is commonly used with such external devices. To this end, a selector 24 is used to selectively couple the IIT 20 of the copying machine with any of these external devices. To obtain a hard copy of the output data of a desired external device, the selector 24 is switched from the IIT to the external device, e.g., a personal computer or a facsimile machine, and the two-level data from the external device is output in the form of a hard copy.
Character data output from the PC or a word processor usually takes the form of JIS or ASCII code data. When receiving this type of code data, the copying machine converts the code data into bit map data by a bit mapping circuit 26, and then transfers the bit map data to the IOT. When receiving the image data from the facsimile, the copying machine decompresses the image data as compressed in the transmitter, into the original image data, and then transmits it to the IOT.
In the digital copying machine of this type which shares the output device of the PC or FAX, the copying machine and the external devices are functionally isolated from one another. Of the output data from those devices, the data which reaches the machine first is accepted for output. Thus, the digital copying machine is a mere combination of the copying machine and the external devices. The printer of the PC, for example, is also used by the copying machine.
Let us consider a case where a set of documents, which may consist of hand-written documents, prints that can be used as original documents for a digital copying machine, and documents electronically prepared by a PC or a word processor (WP), is prepared by using a digital copying machine having both the copying function and the printing function of the external device. In this case, the electronically prepared documents are printed out in the form of hard copies. These hard copies are then combined with the hand-written documents and the combined documents are properly edited to form a set of documents to be copied. Then, the set of documents are read and copied by the digital copying machine, and output in the form of copies from the copying machine.
The preparation of documents in the manner just described consumes a great deal of time and labor.
The documents electronically prepared by the PC or the WP consist of digital data. When digital data is input at the digital copying machine and copied by the copying machine, the image quality of the hard copies is excellent. However, when the electronic documents are printed out as hard copies by a PC or WP, and the hard copies are then input to the digital copying machine and copied, the image quality of the output copies is relatively poor.
Documents received by a facsimile are widely used. In the facsimile, electrical signals obtained by an image read device are processed under a predetermined rule, and are transmitted in the form of digital signals. Accordingly, the image signal of the facsimile can be decoded and input to and printed by the electrophotographic printing unit. However, when the documents derived from the receiver of the facsimile are copied by the electrophotographic copying machine, the image quality of the resultant image is inevitably degraded.